Who cares about solar cells? Why do materials matter?

Solar cells are pretty cool! They take energy from the sun and convert that energy into electricity (the stuff that powers your lights and computers). In previous posts, we have talked about energy and charge. We have shown you a video describing how solar cells work and allowed you to play with a simulated solar cell to learn about light (photons, the basic unit of light) absorption. If you have any question about what words mean, check out our glossary page or message us.

We care about solar cells. Solar cells may be used to reduce our reliance on fossil fuels like coal or gasoline, which may become more scarce and therefore expensive in the future. They can be made in ways the pollute the environment little. They can provide energy to regions of the world where it isn't practical to string wires to power plants. They are used in war zones and in space. They are used to power homes and businesses. 

Why do materials matter? The materials play a major role in determining the efficiency of the cells. Efficiency describes how much of the energy you get out of a cell that has a certain amount of energy from the sun coming in. You want to get a lot of energy out of the cell. Solar cells using the photovoltaic effect must include semiconducting materials to operate. Not all semiconductors are created equal. Some have favorable defects and some have unfavorable defects. Some absorb more light than others. Some absorb light of the sun's energy more efficiently than others. Some materials are more expensive or abundant than others. The techniques used to produce the material impact the number and types of defects found in a material. These techniques can also add cost to the cells, making people less willing to buy them.

The material that our group researches absorbs light really well and is composed of some pretty abundant and inexpensive elements. It is also more tolerant of defects than many competing technologies. However, devices using this material, so far, are not as efficient as cells built with some other materials like silicon, CdTe, or CIGS. This is why we research it. We need to better understand the fundamental materials science of this material (thermodynamics and kinetics) in order to better design techniques to produce the material. We do this by both experiment and computational modeling. We also need to better understand how solar cells can better be used.

What do you think? Can you think of other times when the material something is made of matters? How? Have you ever thought of the sun as an energy source? Have you ever seen a solar cell? Many calculators have them.